Capital Gains on Second Home

What is the name of your state?
South Carolina
We have refinanced our primary home in SC to buy a condo in TN. We are selling our lot in a private campground in TN that we bought for $6,000 and will sell for around $30,000. We plan to use that money on the principle of our primary home mortgage. If so, will we have to pay capital gains?

Yes, you will have to pay capital gains tax on the income. There is no exclusion for reinvesting the money in a new home.